GeoDatabaseModellingUsingCaseTools

Geo-Database Modelling UsingCASE toolsDesign, Modelling and Documentation of the NZERN Geo-databasesProcessed byChristian Schreiner23/12/2005Christchurch, New ZealandChristian Schreiner 2005/2006 iCONTENTS1PROJECT DESCRIPTION (1)2OBJECTIVES (1)3METHODOLOGY (2)3.1L ITERATURE R EVIEW (2)3.2E XPLORING D ATASETS AVAILABLE ON THE NZERN SERVER (2)3.3R EGULAR GROUP MEETINGS AND DISCUSSIONS AMONG GROUP MEMBERS (3)3.4ESRI V IRTUAL C AMPUS C OURSES: (3)3.4.1Using CASE Tools (3)3.4.2Creating, Editing, and Managing Geodatabases for ArcGIS 9 (4)3.4.3Working with Geodatabase Precision and Spatial Domain (4)3.5U SE OF ONLINE SUPPORT SYSTEMS (4)3.6D OCUMENTING DATABASE DESIGN USING THE G EODATABASE-D IAGRAMMER (5)4NZERN GEO-DATABASE MODELS (6)4.1H YDROGRAPHY (6)4.1.1Purpose (6)4.1.2Data structure (6)4.2O BSERVATION (7)4.2.1Purpose (7)4.2.2Data structure (7)4.3R ESTORATION (7)4.3.1Purpose (7)4.3.2Data Structure (7)5TROUBLESHOOTING, HINTS AND TIPS (8)5.1P REREQUISITES (8)5.2I NSTALLATION STEPS (8)5.3I NTRODUCTORY TUTORIAL (9)5.4“A N ERROR OCCURRED WHILE PARSING THE XML DOCUMENT.” (10)5.5“N O OBJECT ID AND NO PROPER GEOMETRY FIELD DEFINED” (10)5.6G EODATABASE D IAGRAMMER (11)6CONCLUSION (13)READINGS (14)APPENDICES (15)Christian Schreiner 2005/2006 13 METHODOLOGY3.1 Literature ReviewThe first step in getting into the topic was scoping the literature available on the web as well as in the NZERN and University libraries. The literature reviewed did not merely cover topics such as geo- database design, but also more specific publications about the ArcHydro Model itself. A detailed list of all the reviewed and used literature is included in the appendix.The most important document has been the ArcHydro book, as it includes all the relevant information about the particular components of the ArcHydro model which has been used as a template to develop one of the NZERN Geo-databases, the hydrography one.3.2 Exploring Datasets available on the NZERN serverOne crucial step in the whole project process was taking a decent look at the already existing data structure on the NZERN server in order to gain a better insight into the organisations structure, tasks, as well as potential requirements for the geo-database layout to be developed. A list of all the datasets with all the relevant shape files, tables, etc. has been available in one MS Excel spreadsheet that provided a good overview about the status quo.Datasetfigure 1: NZERN GIS-datafigure 2: geo-database diagrammer4the freshwater systems. All those datasets, examined in the book “ArcHydro GIS for Water4.2 Observation4.2.1 PurposeThe “observation” model represents sites observed by one or several of NZERN’s volunteers. Depending on the level of accuracy when collecting the data, the observation sites can be points, lines or polygons. In general, those sites could stand for any kind of observation made, such as a water sample location.4.2.2 Data structureThe “observation” data model is not as complex as the “hydrography” model as it merely represents various locations and the link between those locations and a table containing information about the person who carried out the observation and what kind of observation it was. This simple data structure requires only one dataset with a few feature classes and one related table. For further information, see “observation” data model poster.4.3 Restoration4.3.1 PurposeThe “restoration” model contains the spatial representation of NZERN’s restoration sites and also the individual projects within those restoration sites, represented by project areas or if not available just the project centre point. All those project sites have to be within one particular restoration site.4.3.2 Data StructureThe database model consists of merely one feature dataset containing the relevant feature classes for the restoration sites and project sites. Several relationship classes and a topology rule manage the data correctness. For further information, see “restoration” data model poster.5.4 “An ERROR occurred while parsing the XML document.”This error can occur when trying to run the semantic checker in MS Visio in order to validate the developed model. This seems to be a quite common problem as ESRI provides an individual help document for this issues on their support website.Error MessageSchema Wizard returns an error when importing a XMI file:"An error occurred while parsing the XML document. Error number : 516"CauseThe uml.dtd file does not exist in the same directory as the XMI file.Solution or WorkaroundThe file uml.dtd must be present in the directory that contains the XMI files.1. Copy the uml.dtd file from the appropriate location. For ArcGIS 8.x, the defaultlocation would be C:\ArcGIS\arcexe83\CaseTools\Utilities. For ArcGIS 9.0, the default location would be C:\Program Files\ArcGIS\CaseTools\Utilities.2. Paste the uml.dtd file in the same folder as the XMI file being used.5.5 “No OBJECT ID and no proper geometry field defined”Trying to run the semantic checker for one of the models (restoration) the semantic checker log file did give out the message that there is no OBJECTID and that the geometry field has not been defined correctly.Solution or WorkaroundAlways check on the correct direction of the arrows linking the inheritance class to the object class. If the arrow is the wrong way, the object class cannot inherit any attributes from the inheritance class, such as OBJECTID or Geometry.For further information see the ESRI documentation and the tutorial.5.6 Geodatabase DiagrammerOne good possibility to maintain a consistent documentation layout and a high standard of visualisation is the use of the Geodatabase Diagrammer, which allows the user to create standardised Visio diagrams of his or her geo-database layout.The results can further be changed and modified in Visio or for a more sophisticated design in Adobe Illustrator or Corel Draw. The data model poster available on the ESRI homepage have all been created with this diagrammer and have further been designed in Adobe Illustrator.Figure 3: geodatabase diagrammer start6 CONCLUSIONDocumenting the Geodatabase design is a worthwhile part of each GIS project and can help to achieve greater quality outcomes as well as it provides the user with a tool to distribute and communicate the Geodatabase design to other GIS users as well as to lay people.CASE tools can help to achieve this objective and are very useful for large and sophisticated databases rather than for small, simple ones. They require the user to have at least basic skills in object oriented modelling and a good overall knowledge about Geodatabase design itself to develop a model that fits a company’s needs and is extendable when necessary. In retrospect, it can only be recommended to do extensive study about Geodatabase design and CASE tools (e.g. free tutorial and virtual campus course) before designing the first database from scratch or by customising a given model, such as the ArcHydro or Parcel model template.One can say, that even for small and simple databases, documenting the final design with the Geodatabase diagrammer is an simple and time efficient step to get a document that can easily be read and understood by other people, even with minor experience in GIS.APPENDICESAppendix I: Hydrography model poster Appendix II: Observation model poster Appendix III: Restoration model poster。